/*
 * Copyright (c) 2011-2014 Pivotal Software, Inc.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.camunda.bpm.extension.reactor.projectreactor.selector;


import java.util.function.Predicate;

/**
 * {@link Selector} implementation that uses the {@link #hashCode()} and {@link #equals(Object)}
 * methods of the internal object to determine a match.
 *
 * @param <K> The type of object held by the selector
 * @param <T> The type of object held by the selector
 * @author Jon Brisbin
 * @author Andy Wilkinson
 * @author Stephane Maldini
 */
public class ObjectSelector<K, T> implements Selector<K>, Predicate<K> {

  private final Object monitor = new Object();
  private final T object;

  /**
   * Create a new {@link Selector} instance from the given object.
   *
   * @param object The object to wrap.
   */
  public ObjectSelector(T object) {
    this.object = object;
  }

  /**
   * Helper method to create a {@link Selector} from the given object.
   *
   * @param obj The object to wrap.
   * @param <T> The type of the object.
   * @return The new {@link Selector}.
   */
  public static <T> Selector<T> objectSelector(T obj) {
    return new ObjectSelector<T, T>(obj);
  }

  @Override
  public T getObject() {
    return object;
  }

  @Override
  public boolean matches(K key) {
    return !(null == object && null != key) && (object != null && object.equals(key));
  }

  @Override
  public HeaderResolver getHeaderResolver() {
    return null;
  }

  @Override
  public boolean test(K t) {
    return matches(t);
  }

  @Override
  protected Object clone() throws CloneNotSupportedException {
    return new ObjectSelector<K, T>(object);
  }

  @Override
  public String toString() {
    synchronized (monitor) {
      return "Selector{" +
        "object=" + object +
        '}';
    }
  }

}
